Selon Ivan Lucena <lucena_i...@hotmail.com>: > Hi Even, > > > From: even.roua...@spatialys.com > > To: lucena_i...@hotmail.com > > Subject: Re: [gdal-dev] RFC 15: Band Masks vs #5621 > > Date: Wed, 20 Aug 2014 20:39:29 +0200 > > CC: gdal-dev@lists.osgeo.org > > > > > > > > I am trying to help a developer how wants to use VRTs as an intermediary > > > between a GeoRaster and a PNG, in order to produce thumbnails. In that > > > case, does the VRT needs to describe the mask band so that the PNG's > > > driver will received the filtered image, with the zeroes regions masked > > > out? > > > > You need to explicitely declare mask bands in the VRT. See the VRT > > documentation for that. But that will just declare the existence of the > mask > > band, and will not do any processing such as zeroing masked regions. > > You are right. GDAL can copy the mask from one dataset to another, depending > on the driver. > > But there is no way to indicate that you want the result of the masking, not > in the API, not on command line tools. > > Maybe we should add that to the wish list.
Eh eh seems there is no limit to the wish list ;-) More seriously, I can imagine this could be done through a new VRT mechanism, that could be triggered by a new option of gdal_translate That would be mostly needed for per-band mask, since for per-dataset mask, you can already trick the mask to be considered as an alpha band (e.g. gdal_translate -b 1 -b 2 -b 3 -b mask in.tif out.tif will transform a RGB+mask into a RGBA dataset). For per-band mask, the value of the pixels that are masked should also be specified in the VRT syntax. Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev